Many devices utilize a normally-closed or normally-open switch. Such switches often have a push button that is biased into an extended position. When the push button is in the extended position, the switch is in its normal state. For a normally-closed switch, the circuit is closed in its normal state with a moveable terminal in contact with a stationary terminal. For a normally-open switch, the circuit is open in its normal state with a moveable terminal disengaged from a stationary terminal. As a force is applied to the push button, the push button rotates into the housing of the switch. Such rotation of the push button causes the moveable terminal to move relative to a stationary terminal. In a normally-closed switch, this movement causes the moveable terminal to break contact with the stationary terminal, thus opening the circuit. Conversely, in a normally-open switch, this movement causes the moveable terminal to make contact with the stationary terminal, thus completing the circuit.
One problem that commonly occurs with such normally-closed switches is that, in some cases, the circuit never opens. For example, many refrigerators and freezers have an interior light that is off when the door is closed, but is on when the door is open. To turn such a light on or off in response to the movement of the door, a normally-closed switch is commonly installed near the door of the refrigerator or freezer. However, improper installation of the switch can lead to the circuit not opening, especially when there is a lack of quality control by the manufacturer with respect to ensuring the correct gap between the liner and the door relative to the switch location. Further compounding this problem, when the internal post member moves downward and causes the moveable terminal to break contact with the stationary terminal, it has also been observed that there is often some slight movement of the stationary terminal. In other words, the stationary terminal may move with the moveable terminal to some extent, resisting the disengagement of the moveable terminal from the stationary terminal.
Commonly assigned and co-pending U.S. patent application Ser. No. 14/185,625 describes a solution to this problem. In U.S. patent application Ser. No. 14/185,625, which again is incorporated herein by reference, the normally-closed switch further includes one or more positive stops engaging the stationary terminal at a predetermined position in the movement of the stationary terminal. Thus, the stationary terminal is prevented, at a given point, from any further movement with the moveable terminal, at least beyond the predetermined position. In other words, the positive stops substantially eliminate any resistance to the disengagement of the moveable terminal from the stationary terminal. And, as a result, the normally-closed circuit opens and closes more consistently.
There remains a need for an improved construction for such a normally-open switch that similarly ensures that the circuit opens and closes more consistently.